Whorled View

April 25, 2008

REALITY CHECK: Electric Vehicle Fueling Stations

I thought this wasn’t doable until I ran the numbers. See … it depends on how the Electric Vehicle (EV) is built. You can trickle charge them overnight, or you can rapid-charge them in a matter of minutes if you have enough juice, but the battery must be designed for one method or the other. Right now they’re all designed for trickle charging overnight.

The problem with rapid (5 minute) charging is the amount of energy throughput required. The electrical grid would need some massive restructuring to provide the kind of throughput needed, which is very very expensive. The other option, which is far more likely than to get the power companies to do anything, is to generate it onsite via wind power or solar power.

The wind power is a slam dunk. Just one of these windmills can easily generate enough to charge 6 cars at a time … assuming it’s windy enough. This would be a no-brainer in many places. The Windmill will be around $500,000. The whole thing (including infrastructure power conditioning, and storage) should cost around $1.5 M. Not bad. No wonder wind power is by far the fastest growing renewable.

Solar is a little trickier. Ideally you’d put your panels over a parking lot for a shopping center or supermarket. You could also put them directly on top of the shopping center or supermarket, but I think a covered parking lot would be desirable enough for the shoppers such that the owners would probably provide the parking lot solar space for free. To support rapid filling 6 cars simultaneously you’re going to need about 6 acres of panels. A large parking lot should provide this, assuming that the panels will only cover parked cars. If more space is needed, a patchwork could be put over the low-traffic areas.

That’s not bad (I expected the space requirements to be more demanding). How about cost? About $3.5 million just for the solar array. Add another $2M for infrastructure (including panel supports, wiring, energy storage, and power conditioning) and you’re into it about $5.5 million. Sounds like a lot (especially compared to wind power), but if you charge $0.05/mile, which is about 1/4 of what gas currently costs for most Americans right now, you can turn a profit.

How much profit? At $0.05/mile you’ll be selling energy at twice the rate that grid normally costs, or $0.17/kWh. Assuming that the cars will be charged at a rate of 500kW (167W/car), and that you’ll charge an average of 3 cars (a generous assumption, imo) at a time between the hours of 7am and 10pm (15 hours), you’ll gross about $465k/yr from motorists. Then you’ll sell the excess back to the grid generating an additional $150k/yr (remember you’ll be using some of this excess in the evening and in some seasons). That’s not bad, but it’s not spectacular considering your loan and the costs of running such a business. In fact, it’s not much better than what you’d make just selling all the electricity back to grid, which is what you’ll do with the excess anyway. If you sell it back to grid you’ll still make about 70% as much per kWh, without having to deal with the bother and costs of running an EV Fueling Station.

Here’s the kicker though … just about the time you’ll have the original loan paid off … say in 20 years, it will be time to replace all the solar panels, costing you another $1.8M in today’s dollars (assuming solar prices will have dropped in half), but at least after that your net will be higher than it was with the original loan.

Still every penny counts when you run a business, so it looks like a good deal, and you’ll be providing a service to the EV community. It is however contingent on three extremely critical things: 1) that it’s sunny, and 2) that they build cars for rapid charging 3) that people will rapid charge their car at 2X the cost of what it costs them to do it at home overnight.

This last point sinks the whole deal for me. If convenience and the mighty dollar is king (and I think it is) people would prefer to just plug in their car when they get home, saving them money over the cost of rapid charging at the supermarket. If someone forgets to plug in their car at night, they’ll just generate their electricity on the fly with a built-in gas-powered generator. That is, incidentally, how they’re making the next generation hybrids, and all future EV’s will likely have that feature so you’ll never be stranded.

So there you go. Conclusion: Based on my analysis EV’s will NEVER be rapid charging nor will Electric Vehicle Fueling Stations exist for rapid charging purposes. That is unless all the solar cell manufacturers are bought up by the oil companies who then will then get into bed with the auto manufacturers, who will then agree to only make rapid-charge EVs that can only be charged in EV fueling stations (not at home).

Now that’s a scary thought. If that happens (doubtful) then this is a viable business. Due to the high upfront costs it’s maybe twice as profitable as a normal gas station is today (based on my google research). But in this scenario where Automakers produce only rapid-charge EVs, which I think is unlikely, this would be a sure thing. Note that there will be limited places where this can be done: shopping centers and supermarkets where there is enough space to also put a gas-station-sized EV station.

PS- here’s the math for those who like math:

Solar Array Energy Generating capability:
Most of the EV cars over the next 10-15 years will likely have 15kWh storage capacity as Advanced Li-Ion batteries. These batteries can be made to completely charge in 5 minutes, but that’s like 15kWh in 5 minutes, and if you have 6 cars doing that simultaneously, that’s 90kWh in 5 minutes That requires a energy generation capability of 90000Wh *(60min/h)/(5 min) = 1MW (approx).

Solar Panel Space Requirements:
On average a good 3×8 panel will provide about 100 Watts, so you’ll need 10,000 of these panels (minimum) assuming it’s sunny all day (1M/100=10,00 panels). That will take up 6 acres of panels (3ftx8ft*10,000 = 240,000ft^2 = 6 acres).

Solar Panel Cost:
Today if you buy in bulk and if you’re lucky you can get solar panels at $3.5/Watt. This cost has not changed much in the last 10 years. It isn’t expected to drop much in the next 10-20 years even with an explosion of supply simply because demand is so high, and as soon as the price drops demand increases to stabilize the price. 1 Million W at 3.5/Watts = $3.5 Million just for the solar array (infrastructure not included).

Gross Annual Income:
($0.17/kWh which is what you’re charging) * (500kW used to charge 3 cars continuously) * (15 h/day) * (365days/yr) = $465k



  1. David, you are such a smartypants.

    I think wind power is awesome. Wouldn’t it be cool to have a windmill at the cabin?

    Comment by Sally — April 28, 2008 @ 1:30 am

  2. A windmill at the cabin would be awesome, but with the river geothermal would be cool too.

    Comment by davea0511 — April 28, 2008 @ 5:28 pm

  3. Incidentally, a old friend of mine and his wife visited with us over the weekend, who designs substations for wind farms. Apparently 20% of our nation’s energy could come from wind … and probably will. It’s cheaper in many areas than building coal plants, or even upgrading existing coal plants so they’re complaint. They’re starting to build off-shore windmills that will produce as much as 5 MW. That’s enough to power 3000 homes … of a single windmill. Yeah … wow. All the easy places are already taken though. Now they’re building infrastructure to put windmills in far out places (like off-shore), where most of the cost is not the windmill but in the cable and infrastructure required to transport the energy to a point on the grid so the energy can be used.

    Pretty cool stuff.

    Comment by davea0511 — April 28, 2008 @ 5:40 pm

  4. I’m impressed.

    Comment by salt h2o — April 30, 2008 @ 3:17 am

  5. I like learning about this stuff. Joe’s uncle lives completely off the grid–and have for several years. They have wind mills, and one in particular that is HUGE and really cool. Also solar. Their fridge is skinny and small, and they line dry their clothes. They don’t have any children–I think that makes it more doable. Don’t own any interesting alternative-fuel cars yet, but they do have a yellow bug that is designed/shaped like Pica-chu (japanese cartoon) that they got on ebay. It is hilarious, and Ruby loves it.

    Comment by Jolly — May 28, 2008 @ 8:32 pm

  6. Joe’s uncle sounds cool. I’d like to meet him sometime.

    Comment by lullabyman — May 29, 2008 @ 4:52 pm

  7. Well, if they remain on a trickle charge basis, there is one location where lots of people’s cars tend to stay in one spot for a good 8 hours besides their homes – work. Therefore, the economics of the charging stations might work out better if done at the workplace – and given that you have the same customers over and over in this scenario, the company would be free to either charge the same as they get selling back to the grid, or treat it as an additional benefit for employees. Wouldn’t require any kind of switch from trickle to rapid recharge, either.

    Comment by Scott H — July 17, 2008 @ 7:37 pm

  8. >there is one location where lots of people’s cars tend to stay in one spot for a good 8 hours besides their homes – work

    Yeah, this is a great point. I’d say that’s one more reason cars should be made for trickle charging.

    Comment by Dave Austin — July 17, 2008 @ 9:22 pm

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    Comment by PowerNature — September 29, 2010 @ 4:24 am

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